The present invention relates to an adjustable magnetic device.
A magnetic tripping device such as a solenoid generally comprises a coil or winding of wire through which a current is passed. The solenoid is configured to manipulate an actuator when the electromagnetic force generated by the coil exceeds a predetermined value of the solenoid.
The actuator is generally biased by a mechanical force in an opposite direction of the force generated by the electromagnetic field of the coil. This force is typically provided by a spring or other mechanical means wherein a plunger of the actuator is biased with respect to a stator positioned opposite to the actuator.
In addition, an air gap is positioned in between the actuator and a stator. The air gap is also located within the coil and provides an insulating barrier to the force generated by the electromagnetic field of the coil.
Accordingly, the tripping or predetermined tolerances of a solenoid are dependent upon the mechanical biasing force and the size and positioning of the air gap.
Moreover, the required range or predetermined tolerances of a magnetic tripping device vary in accordance with user""s requirements such as the circuit loading.
Most solenoids are either fixed (nonadjustable) or have a single means of adjustment for either the air gap or biasing force.
In an attempt to accommodate these varying tolerances, an adjustable trip solenoid has been developed wherein the air gap between the stator and the actuator can be varied. However, the varying of this air gap also causes the spring biasing force to vary. Moreover, these changes are opposite with respect to each other. For example, increasing the air gap will also increase the biasing force of a spring.
Accordingly, there is a need for an adjustable solenoid wherein the air gap and mechanical biasing force can be varied so that as the air gap is decreased the mechanical biasing force is also decreased, and vice versa.
In an exemplary embodiment of the invention, an adjustable solenoid provides an adjustable air gap where the mechanical biasing force of the solenoid is either decreased or increased as the air gap is increased or decreased.